Phosphorus is essential to the growth of algae. Because of noxious algal bloom that occurs in surface waters, there is much interest in controlling the amount of phosphorus compounds that enter lakes, rivers and other bodies of water from domestic and industrial waste discharges and natural runoff.
Phosphorus is typically removed from wastewater biologically or chemically. Chemical treatment typically utilizes a chemical such as calcium, iron or aluminum to precipitate phosphorus-containing compounds such as ferric hydroxyphosphate. There are drawbacks and disadvantages to chemical treatment. First, regulatory agencies continue to place more stringent phosphorus reduction demands on wastewater treatment plants. In some cases, wastewater treatment plants are required to reduce phosphorus concentrations to 0.05 mg/l or even lower. It is neither practical nor feasible to accomplish such low level phosphorus reduction by conventional chemical precipitation. To even attempt to achieve low level phosphorus concentrations through chemical treatment, requires increased chemical dosage. This, of course, dramatically increases the cost of chemical treatment. At the same time, with this approach the chemicals are underutilized and wasted because they are not fully reacted with in the process and the unreacted chemicals are disposed of as sludge.
There has been and continues to be a need for a practical and cost effective chemical process for reducing phosphorus concentrations to very low levels.